<template>
    <div>
        <h1>当前求和为：{{ sum }}</h1>
        <select v-model.number="n"><!-- 写冒号:value和.number都能为数字类型 -->
            <option :value="1">1</option>
            <option :value="2">2</option>
            <option :value="3">3</option>
        </select>
        <button @click="increment">+</button>
        <button @click="decrement">-</button>
        <button @click="incrementOdd">当前求和为奇数再加</button>
        <button @click="incrementWait">等一等再加</button>
    </div>
</template>

<script>
export default {
name:'Count',
data(){
        return {
            n:1,
            sum:0
        }
    },
    methods:{
        increment(){
            this.sum+=this.n
        },
        decrement(){
            this.sum-=this.n
        },
        incrementOdd(){
            if(this.sum%2){
                this.sum+=this.n
            }
        },
        incrementWait(){
            setTimeout(()=>{
                this.sum+=this.n
            },500)
        }
    }
}
</script>

<style>
button{
    margin: 0 10px;
}
</style>